Conventional non-volatile memory (NVM) cells are routinely used in electronic circuitry, such as electronic consumer devices. A typical non-volatile memory cell often includes multiple transistors with a floating gate. A charge stored on the floating gate typically represents the logical value stored in the non-volatile memory cell.
Drain avalanche hot carrier (DAHC) injection and Fowler-Nordheim (FN) tunneling are two common techniques for programming and erasing conventional non-volatile memory cells. For example, drain avalanche hot carrier injection can be used by applying a high voltage at the drain of a program transistor in a non-volatile memory cell. This generates a large electric field at the drain of the program transistor, which accelerates electrons onto the floating gate and programs the non-volatile memory cell. As another example, Fowler-Nordheim tunneling can be used by applying a high voltage at a control gate of the program transistor in the non-volatile memory cell. This generates an electric field through a gate oxide separating the program transistor from the floating gate, allowing electrons to reach the floating gate.
Drain avalanche hot carrier injection and Fowler-Nordheim tunneling have various drawbacks. For example, these techniques may require a large electrical current in order to program a conventional non-volatile memory cell, such as several hundred microamps. As a result, power consumption in the conventional non-volatile memory cells is high. Moreover, this high programming current often limits the number of non-volatile memory cells that can be programmed simultaneously. As a particular example, if the programming current is 200 μA for a single non-volatile memory cell, it may only be possible to program eight bits (eight memory cells requiring 1.6 mA total current) or sixteen bits (sixteen memory cells requiring 3.2 mA total current) simultaneously. Because of this, it may take a relatively long time to initialize or program a large memory array. In addition, Fowler-Nordheim tunneling often has reliability issues related to the use of high voltages.